It is well-known to provide the conventional rural postbox with a signal means whereby to indicate a delivery therein and wherein a simple act of postbox closure opening automatically results in a signal flag movement to a delivery indicating position; see for instance the U.S. Patents to Hollenbach, U.S. Pat. Nos. 4,412,646, issued Nov. 1, 1983 and to Morgrey, 4,570,846, issued Feb. 18, 1986.
For various reasons, these known devices are not fully satisfactory. The Morgrey device, see FIG. 3 therein, and Ulery, U.S. Pat. No. 1,141,024, issued May 25, 1915, are for instance each considered to require an undue number of structural parts and mechanical sophistication. Hollenbach's device relies on the uncertain integrity of adhesive and surface characteristics for mounting purposes and either does not require signal operation as a requisite to delivery with regard to the non-closure receptacle species, or the signal device of FIGS. 8, 9 may be operated independent of closure movement.
Other devices for the purpose are sold disassembled, since the mechanics and design thereof would otherwise require awkward packing and handling.